20 Global Climate Change

Overview of Chapter 20 Introduction to Climate Change Causes of Global Climate Change Effects of Climate Change Melting Ice and Rising Sea Level Changes in Precipitation Patterns Effects on Organisms Effects on Human Health Effects on Agriculture Dealing with Global Climate Change

Reforestation in Ghana Question is “how can we mitigate effects of climate change?” Carbon Mitigation Initiative Most dangerous consequences at doubling of pre-industrial levels Certain steps in many areas can reduce effects Increase fuel economy Carbon capture and storage Many more

Introduction to Climate Change: Mean Annual Global Temperature 1960–2010 20 warmest years (since ~1880) have occurred since 1990

Climate Change Terminology Greenhouse Gas Gas that absorbs infrared radiation Positive Feedback Change in some condition triggers a response that intensifies the changed condition Infrared Radiation Radiation that has a wavelength that is longer than that of visible light, but shorter than that of radio waves

Climate Change Terminology Greenhouse Effect Natural trapping of heat in the atmosphere; greenhouse gases absorbs energy and keeps it from leaving Radiative forcing Capacity of a gas to affect the balance of energy that enters and leaves Earth’s atmosphere

Introduction to Climate Change Evidence for Climate Change 20 warmest years since mid-1800s have occurred since 1990 Phenological spring in N. hemisphere now begins 6 days earlier (date the buds of specific plants open) Sea level rise - <2cm/decade for most of 20th century, now ~3cm/decade Warming is not due to natural causes Human produced greenhouse gases are most plausible explanation

Greenhouse Gases Greenhouse gas concentrations are increasing

Causes of Climate Change Increased concentration of CO2 (right) Burning fossil fuels in cars, industry and homes Deforestation Burning of forests

Greenhouse Effect Enhanced greenhouse effect Build up of greenhouse gases (CO2 and others) due to human activities

Pollutants That Cool the Atmosphere Atmospheric Aerosols Both human and natural sources Tiny particles (or sulfur) that remain in troposphere for weeks or months Sulfur-laden layer in the atmosphere reduces the amount of sunlight reaching earth Complicates models of climate change Aerosol effect Atmospheric cooling that occurs where and when aerosol pollution is the greatest

Climate Models Climate affected by: winds, clouds, ocean currents, and albedo Albedo – measure of reflectivity (ice greater albedo than asphalt) Used to explore past climate events Advanced models can project future warming events Models are only as good as the data and law used to program them They have limitations

Climate Models

Climate Models Environmental feedbacks are complicated Positive or negative feedbacks More cloud production can result in a negative feedback Most models project climate a few decades or a century from now Based on different abatement strategies which will affect future CO2 concentration

Unpredictable and extreme climate change We are projecting future climate with incomplete knowledge of environmental feedbacks Using solid scientific understanding, however environmental complexities abound Tipping points? A large rapid change occurs Examples Ocean conveyor belt affected by melting of freshwater in Arctic Polar vortex – cold air from poles move toward equator

Effects of Global Climate Change Wildfire in California

Effects of Global Climate Change- Melting Ice and Rising Sea Levels IPCC projects sea-level rise of18-59cm by 2100 Sea level rise caused in 2 ways Thermal Expansion Melting of land ice Melting has positive feedback Increased melting decreases ice, which decreases albedo leading to further warming

Grinnell Glacier, Glacier National Park 1938 1981 1998 2005

Case-In-Point Impacts in Fragile Areas Eskimo Inuit live traditional life dictated by freezing climate Climate change is altering their existence Wildlife displaced Reduced snow cover and shorter river ice seasons Thawing of permafrost (right)

Effects of Global Climate Change- Changing Precipitation Patterns Some areas will get more water, some areas will have greater droughts

Effects of Global Climate Change- Effects on Organisms Zooplankton in parts of California Current have decreased by 80% since 1951 Affecting entire food chain Species have shifted their geographic range Migrating birds are returning to summer homes earlier Ecosystems at greatest risk of species loss (short term): coral reefs, mountain ecosystems, coastal wetlands, tundra, and polar areas

Effects on Organisms - Coral Reefs Coral reefs can be bleached (right) due to increase in water temperature Affects coral symbiontes and makes them more susceptible to diseases

Effect on Organisms - Vegetation

Effects on Human Health

Effects on Agriculture Difficult to anticipate Productivity will increase in some areas and decrease in others Rise in sea level will inundate flood plains and river valleys (lush farmland) Increase in drought frequency Effect on pests is unknown Warmer temperatures will decrease soil moisture - requiring more irrigation Location (i.e., elevation and altitude) where certain crops can be grown will change

International Implications of Climate Change Developed vs. Developing countries Differing self- interests Differing ability to meet the challenges of climate change

Dealing with Global Climate Change Two ways to manage climate change Mitigation: Limiting greenhouse gas emissions to moderate global climate change Adaptation: Learning to live with environmental changes and societal consequences brought about by global climate change

Relationship Between Mitigation and Adaptation

Dealing with Global Climate Change - Mitigation Locate/invent alternative fuels to fossil fuels Increase efficiency of cars and trucks Carbon Capture and Storage Plant and maintain trees to naturally sequester carbon Geoengineering Global scale projects to mitigate effects Example: seeding ocean with iron to stimulate phytoplankton growth and CO2 storage in deep ocean

Dealing with Global Climate Change - Adaptation Rising sea levels and coastal populations Move inland Construct dikes and levees Adapt to shifting agricultural zones NYC sewer line Climate change refugees People having to leave homes because of climate change effects Example: rising sea levels, storm surges

International Efforts to Reduce Greenhouse Gas Emission Kyoto Protocol Legally binding Provides operational rules on reducing greenhouse gases By 2014, 192 countries had ratified it US has not sign it - it will be difficult to implement without US backing EPA is taking it upon itself to define laws associated with CO2 reduction in U.S. Obama administration meetings with other nations